<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style type="text/css">
		#div1{
			width: 100px;
			height: 100px;
			background: red;
			position: absolute;
		}
	</style>

	<script type="text/javascript">
		//鼠标按下
		//鼠标抬起
		//鼠标移动

		window.onload=function(){
           //console.log(window.screen.availWidth);
		   var oDiv=document.getElementById('div1');
           var disX=0;
           var disY=0;
           //alert(oDiv);

		   oDiv.onmousedown=function(ev){
             var oEvent = ev||event;
             //pos=getpos(oEvent);
             //鼠标的位置减去DIV的位置

             if (oDiv.setCapture) {

             disX=oEvent.clientX-oDiv.offsetLeft;
             disY=oEvent.clientY-oDiv.offsetTop;
             
	           oDiv.onmousemove=function(ev){
	           	 var oEvent = ev||event;
                 var l=oEvent.clientX-disX;
                 var t=oEvent.clientY-disY;
                 
	             oDiv.style.left=l+'px';
	             oDiv.style.top =t+'px';

	           };

		       oDiv.onmouseup=function(){
			    	oDiv.onmousemove=null;
			    	oDiv.onmouseup=null;

			    	//在使用了事件捕获之后，在鼠标抬起的时候。需要释放这个事件捕获，不然的话，无法进行任何操作
			    	oDiv.releaseCapture;
			   };
               
               //在IE7下使用事件捕获，确保所有的事件都指向DIV
               oDiv.setCapture();

               return false;

             }else{
	             disX=oEvent.clientX-oDiv.offsetLeft;
	             disY=oEvent.clientY-oDiv.offsetTop;
	             
		           document.onmousemove=function(ev){
		           	 var oEvent = ev||event;
	                 var l=oEvent.clientX-disX;
	                 var t=oEvent.clientY-disY;
	                 
		             oDiv.style.left=l+'px';
		             oDiv.style.top =t+'px';

		           };

			       document.onmouseup=function(){
				    	document.onmousemove=null;
				    	document.onmouseup=null;

	
				   };
	               
	  

	               return false;
	             }


		    };
	
};
	</script>
</head>
<body>
64764646464<br>
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<div id="div1">7567575</div>
5765757567657
</body>
</html>